"It's not what you know, but who you know." Right?

That used to be true, but it's not true anymore.  It doesn't matter as much who you know, but what matters is who knows you. In other words, what is really important is that we create awareness.

If They Don't Know You, It Doesn't Count
If you think you have a connection with somebody just because you know them, it doesn't necessarily mean that you have a connection if they don't know who you are back.

Focus on the people that you know also knowing who you are and what you are up to. And that means you need to create awareness. 
Nowadays it's very easy to self promote, and it's something that you have to do. And in order to uncover job opportunities that the general public doesn't know about, people have to be aware of what you're up to and the fact that you are looking for opportunities.

Let People Know What You're Doing
"Hey, I am in the market I am available for a job." Let everybody know what you're up to and what you're looking for. Create awareness with them to let them know that you're looking for something. So that if they come across some opportunity, you're going to be top of mind. You're going to be the first person they think of.

Create awareness about you and your professional situation and your professional goals, so that other people will keep you top of mind.